SOLUTION: Five white and four black balls are arranged in a row. What is the probability that the end balls are of different colors? Thank You so much ..

Algebra ->  Probability-and-statistics -> SOLUTION: Five white and four black balls are arranged in a row. What is the probability that the end balls are of different colors? Thank You so much ..      Log On


   

Question 1177214: Five white and four black balls are arranged in a row. What is the probability that the end
balls are of different colors?
Thank You so much ..
Found 2 solutions by ewatrrr, greenestamps:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
 9 balls:  5W and 4Bk  (9! ways of arranging 9 Balls)

I. Reserve one of each color for the end spots...leaving 7 balls
The 7 balls can be arrange in 7! ways.

II> P(different colors on both ends = 2*7!/9! (white or black on either end)
 2*7!/9!= 2/9*8 = 1/9*4 = 1/36 = .0278

Wish You the Best in your Studies.


Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


The arrangement of the other 7 balls has nothing to do with the problem.

P(different colors on each end) = P((white first AND black last) OR (black first AND white last))

%285%2F9%29%284%2F8%29%2B%284%2F9%29%285%2F8%29+=+20%2F72%2B20%2F72+=+40%2F72+=+5%2F9